The Multi-distance buffer plugin currently uses the buffer function of QgsGeometryAnalyzer. It returns a polygon dataset with multiple buffer zones and a distance attribute that identifies the different zones. The zones are dissolved, and none of the attributes of the original dataset are preserved.

If you are just looking for visual buffering (not creating the buffers as accurate features), you can utilize the 'new symbology' and build up symbol layers, basing their size on map units. Click 'Change..' under the symbol to add layers. Also, look into rule-based symbols for logical control over what gets visually buffered.